Catheters are widely used in the medical applications. Peripheral or intravenous catheters and infusion set catheters are two frequently used types of catheters. Peripheral or intravenous (IV) catheters infuse medication or other fluids directly into blood vessels. Infusion set catheters are integral parts of infusion sets that deliver medication, such as insulin, into the skin for absorption by the user.
FIG. 1 illustrates a conventional infusion set 10 for use with an infusion set catheter to deliver insulin therapy. The infusion set 10 comprises an extension set, a base 19 and a catheter 14 attached to the base 19. The extension set comprises a hub 12, connector 18, fluid line tube set 16 connecting the hub 12 and the connector 18, and a pump (not shown) connected to the connector 18, such that insulin from the pump is delivered through the catheter 14. An insertion device inserts or attaches the catheter to a user. The infusion set and insertion device can also be combined into one unit.
Another type of insulin infusion device is a patch pump. Unlike a conventional infusion pump, a patch pump is an integrated device that combines most or all of the fluid components in a single housing which is adhesively attached to an infusion site, and does not require the use of a separate infusion (tubing) set. A patch pump adheres to the skin, contains insulin (or other medication), and delivers the drug over a period of time, usually via an integrated subcutaneous catheter. Patch pump and infusion sets need to be reapplied on a frequent basis, such as every three days, as complications may otherwise occur.
Catheters used in infusion sets and patch pumps are similar in construction to peripheral or IV catheters, with the infusion set catheters generally being smaller in size.
A conventional peripheral or IV catheter is illustrated in FIG. 2. The peripheral catheter 14′ is generally made of a polymer, such as Teflon®. The catheter tube 144 is conventionally connected to a rigid metal or plastic wedge 143 which is a funnel-shaped device that attaches the catheter to an adapter or hub 142 of the catheter. A neck portion of the wedge 143 is inserted into an end portion of the catheter tube 144 and the catheter is deformed to frictionally wedge itself into the catheter adapter 142. The catheter 14′ includes an open distal tip 145.
In such construction, transmission of impact or vibration forces can damage the catheter at the point of impact as well as at its connection to the wedge, resulting in a weakened connection and/or leaks at the connection. The weakened connection between the catheter and the wedge may also cause the catheter to break off from the wedge during use.
A complete IV catheter assembly 10′ is illustrated in FIG. 3. This device is available as the BD Nexiva™ Closed IV Catheter System from Becton, Dickinson and Company (BD). The indwelling catheter portion is made of BD's ViaIon™ biomaterial that reduces mechanical phlebitis (caused by irritation of the venous endothelium by the catheter) and infiltration (which occurs when an IV fluid or medication accidentally enters the surrounding tissue rather than the blood vessel), maximizes dwell time, provides kink resistance (resistance of the catheter to be subject to becoming snagged, knotted or sharply bent to form a kink which impedes or blocks fluid flow) and recovery from kinks, and softens in the vessel.
Conventional infusion set and/or patch pump catheters, as well as peripheral or intravenous catheters, are susceptible to damage with normal wear, such as kinking. Conventional infusion set catheters are also sometimes fragile due to their construction and material, and are susceptible to damage due to excessive bounce or vibration in the insertion mechanization of the catheter, via an introducer needle, which may result in excessive force being transmitted to the catheters.